A comparative study of the electrochemical and proton-reduction behaviour of diphosphine-dithiolate complexes [M2(CO)4(μ-dppm){μ-S(CH2)nS}] (M = Fe, Ru; n = 2, 3)

Abstract

Abstract: The electrochemistry of dppm-bridged dithiolate complexes [M2(CO)4(μ-dppm){μ-S(CH2)nS}] (M = Fe, Ru; n = 2, 3) has been studied by cyclic voltammetry. The diiron complexes show similar electrochemical responses in CH2Cl2 but differ significantly in MeCN, while the diruthenium complexes change only slightly with changes in the dithiolate backbone and solvent. Proton-reduction studies in MeCN with HBF4·Et2O as the proton source show that all are active catalysts for proton reduction in their singly reduced state. An additional catalytic event is observed for all, resulting from their partial protonation giving [M2(CO)4(μ-dppm){μ-S(CH2)nS}(μ-H)][BF4]. The diiron complexes show better long-term stability to acids, the diruthenium complexes degrading at high acid concentrations. Graphical Abstract: The electrochemical response of dithiolate complexes [M2(CO)4(μ-dppm){μ-S(CH2)nS}] (M = Fe, Ru; n = 2, 3) has been investigated in different solvents as well as they have been tested as electrocatalysts for the reduction of protons to hydrogen.[Figure not available: see fulltext.].